Question

	Kids	Kids	Kids	Kids	Kids	Kids
cars	1	2	3	4	5	6	TOTAL
1	1	1	2	2	2	2	10
2	4	2	1	3	3	2	15
3	0	2	2	0	0	1	5
TOTAL	5	5	5	5	5	5	30

Use the two-way table above to answer the following question.

1) Find the P(>1car | 3-5kids) ____ ?

	Kids	Kids	Kids	Kids	Kids	Kids
cars	1	2	3	4	5	6	TOTAL
1	1	1	2	2	2	2	10
2	4	2	1	3	3	2	15
3	0	2	2	0	0	1	5
TOTAL	5	5	5	5	5	5	30

Use the two-way table above to answer the following question.

2) Find the P(<4kids or ≥2cars) ____ ?

Answer 1

1)

P(>1car | 3-5kids)

it is a conditional probability question to find the cars>1 given the condition of 3-5 kids

So,total 3-5 kids(3 kid+4kid+5kid) =5+5+5

=15

and

car>1 =(car=2)+(car=3)

	Kids	Kids	Kids	Kids	Kids	Kids
cars	1	2	3	4	5	6	TOTAL
1	1	1	2	2	2	2	10
2	4	2	1	3	3	2	15
3	0	2	2	0	0	1	5
TOTAL	5	5	5	5	5	5	30

now,out of 15 (3-5 kids),find out the number of (=2cars and =3cars),i underlined them

i.e (1+3+3+2+0+0)=9

car>1 =9

so, P(>1car | 3-5kids)=9/15=0.6

2)

let P(A)=P(<4 kids)=P(1kid+2kid+3kid)=(5+5+5)/30=15/30

let P(B)=P(≥2cars)=P(2car+3 car)=(15+5)/30=20/30

	Kids	Kids	Kids	Kids	Kids	Kids
cars	1	2	3	4	5	6	TOTAL
1	1	1	2	2	2	2	10
2	4	2	1	3	3	2	15
3	0	2	2	0	0	1	5
TOTAL	5	5	5	5	5	5	30

=(4+2+1+0+2+2)/30=11/30

=15/30+20/15-11/30=24/30=0.8

P(<4kids or ≥2cars) =0.8